Smoke On Go

The dreaded white coat syndrome!

In any avmed practice, there are two things that take up a lot of time in a day. The first is the paperwork, which never seems to end. What’s the old story about when the paperwork is the same weight as the aircraft? The second thing is blood pressure (BP.) It is the one parameter that seems to trip up the pilots.

Logically, the greater majority of pilots pass their flight medical examination on a routine basis. This means that, amongst other things, the vitals are found to be normal. Which cannot be completely true, for reasons I’ll explain shortly!

Blood pressure is obviously vital for living. But too much of it causes a lot of long-term damage.

Engineers extended the service life of the MD80’s hydraulic system by having the pilot switch the pressure from 3000 PSI to 1500 PSI after take off. Doctors like this approach. Too much blood pressure, or hypertension, stretches blood vessels, damaging the fine endothelial linings that need to stay smooth for good blood flow. It makes the heart work too hard, which may eventually be stretched and then fail. It destroys our filters (read kidneys.) It may pop blood vessels. So everyone agrees, too much pressure is bad stuff. Naturally, we are going to check for it during a flight medical. If we find it, we are going to manage it. We are going to extend your service life.

We can treat hypertension easily enough. But who do we treat? Where do we draw the line?

Blood pressure is measured by obtaining two values, namely the pressure when the heart contracts and when it relaxes. This is called systolic and diastolic pressure. Conventional wisdom says a normal pressure is 120/80 mmHg. Early (stage 1) hypertension has a systolic value of greater than 130 mmHg and stage 2 is a blood pressure of 140/90 mmHg. The CAA draws the line at stage 2. If this is found, it needs definite treatment.

This is the point where it gets tricky. The literature shows that up to 30% of people have ‘white coat’ hypertension, also known as reactive hypertension. This is an abnormally elevated blood pressure that ONLY occurs when at the doctor’s office. I don’t even wear a white coat, but it doesn’t seem to help! At home, the levels are quite normal. The jury is still out on whether this indicates a potential future blood pressure issue, but at present we accept this phenomenon as quite normal. It is part of the ‘fight or flight’ response that is automatically regulated by your body.

Does this mean I temporarily ground 30% of my pilots every day? Of course not. But it does keep me busy! Some literature supports the idea of measuring the blood pressure by means of an automated machine in the waiting room. Given that pilots tend to see this medical as a test, reactive hypertension is probably a lot more prevalent than in the normal population in any case. I’m not convinced the waiting room is a less stressful environment. So what normally transpires is a stretched out consultation during which I try to beat the pilot’s autonomic system into submission by taking a great many readings.

If a normal value isn’t obtained, the pilot is often referred for a 24 hour ambulatory BP test, where the whole measuring contraption is strapped to his or her arm for a day. This works extremely well, but doesn’t cure you from the white coat. It is no use telling me the next year that you had it done previously, so the whole saga repeats.

In my opinion, there is only one real solution. It is home BP surveillance.

Research shows that it is as accurate as a 24 hour test, but without the hassle. If you know you have a highly reactive blood pressure, get yourself an automated cuff from your local chemist. They generally cost a few hundred rand only and are pretty accurate. You are then able to take your own blood pressure twice a day for the week leading up to the medical. Take the readings with during your consultation and things will be a lot easier!

With this approach, there is really no reason to get wound up if you have white coat hypertension anymore.




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